Field of the Invention
The present invention relates to a zoom-type lens barrel mounted on an image pickup apparatus such as a digital camera, and an image pickup apparatus equipped with the lens barrel.
Description of the Related Art
Some lens barrels mounted on image pickup apparatuses such as digital cameras have a zooming mechanism that varies the shooting angle of view by changing the spacing between a plurality of lenses in a direction of an optical axis. For lens barrels of this type, due to demands for higher zoom rate and thinner cameras, a lens group is required to be increased in stroke to the extent possible and the lens barrel is required to be miniaturized in the direction of the optical axis.
Accordingly, when a lens barrel is to collapsed, some of lenses in a lens barrel are retracted outwardly in a radial direction from a center of the optical axis to increase zoom rate and slim down the lens barrel, and by extension a camera (see Japanese Laid-Open Patent Publication (Kokai) No. 2008-46504 and Japanese Laid-Open Patent Publication (Kokai) No. 2012-58354).
According to Japanese Laid-Open Patent Publication (Kokai) No. 2008-46504, however, because a lens to be retracted when a lens barrel is collapsed is disposed outside other lenses in a radial direction, lens diameter needs to be as small as possible in order to reduce the size of the lens barrel in a radial direction, and this imposes a severe constraint on design. On the other hand, according to Japanese Laid-Open Patent Publication (Kokai) No. 2012-58354, the entire lens to be retracted is rotated to an area outside the lens barrel in a radial direction, and hence upsizing of an image pickup apparatus is inevitable.